Less Obesity Found at Higher Elevations

Orison Woolcott, MD

Looking to lose fat? Head for the hills. New research led by the Cedars-Sinai Diabetes and Obesity Research Institute adds to growing evidence that people who live at higher altitudes are less likely to be obese than lowlanders.

Obesity, which involves excessive accumulation and storage of body fat, is a serious health issue because it increases the risk of diabetes, cardiovascular disease, hypertension and several types of cancer. In the U.S., more than one-third of adults are considered obese, according to the federal Centers for Disease Control and Prevention.

The Cedars-Sinai study, published in the April issue of the journal Obesity, analyzed data from 31,549 adults in Peru. It found that men there who lived at an elevation of 3,000 meters (9,843 feet) or more had about a 50 percent lower proportion of cases of overall obesity than those living at 500 meters (1,640 feet) or under. At intermediate elevations, the difference was 26 percent. These men also had less abdominal obesity, which is strongly associated with cardiovascular disease.

The relationship between obesity and elevation in the U.S. also has been the subject of research at Cedars-Sinai. For instance, a 2014 Cedars-Sinai study, also published in Obesity, found that U.S. individuals living at high altitude had 25 percent lower odds of being obese than those living at low elevations.

"Our findings suggest that the adjusted inverse association between geographical elevation and obesity extends to different populations around the world," said Orison Woolcott, MD, a project scientist at the Cedars-Sinai Diabetes and Obesity Research Institute. Woolcott was the first and primary author of both studies. About 500 million adults worldwide are believed to be obese, according to the World Health Organization.

Interestingly, the altitude-related difference in obesity prevalence was not observed in women in either study, when adjusted for other factors such as age, self-reported physical activity, education level and income. "The reason for this finding remains unclear and should be further investigated," Woolcott said.

Why altitude and obesity may be related also remains a mystery. Although it's common for lowlanders to eat less when exposed to high altitudes, the effect of prolonged altitude exposure on appetite is not known. The researchers speculated that the colder temperatures found at high elevations may play a role by forcing the body to burn more calories to keep warm. Ambient barometric pressure also may be a factor.

"Future studies are needed to explore the source of the association between geographical elevation and obesity," Woolcott said.

Discussing the significance of the new study, Richard Bergman, PhD, director of the Cedars-Sinai Diabetes and Obesity Research Institute, said, "Research at our institute is focused on the close relationship between obesity and diabetes. Both have been increasing in tandem. Woolcott's study is important as it may yield insights into which factors at high altitude decrease prevalence of obesity and diabetes. Such insights potentially can be exploited to develop new therapies to reduce these disorders."

Bergman, a professor of Biomedical Sciences and the Alfred Jay Firestein Chair in Diabetes Research, was a co-author of the study.